1. Field of the Invention
This invention relates generally to balancing arrangements, and more particularly, to a holder arrangement for supporting an article to be subjected to a balancing procedure.
2. Description of the Related Art
Tool holders of the type that are generally used in balancing equipment are of standard sizes, illustratively CAT T-30, T-35, T-40, and T-50. Conventional balancing arrangements of reasonable costs generally conform to the standards of ISO balance grade G-2.5. However, since the spindle speeds of machining equipment have steadily increased, there is a need to achieve balance to ISO G-1.0. Conventional balancing arrangements generally are unable to achieve the higher levels of balancing accuracy required by the ISO G-1.0 standard, partly as a result of the conical configuration of the mounting surface of the tool holder. In some known tooling arrangements, the included angle of the mounting surface of the tool holder has a slope of 3.5 inches per 12 inches. In order to balance to ISO G-1.0 standards, the tool holder must spin true to its conical surface and the mass center must be adjusted to within 10 micro-inches of the spinning access.
In known arrangements, tool holders are balanced by placing same into a mating conical hole in an adapter. Alternatively, the tool holder is placed directly in the shaft of the spindle, occasionally with a drawbar mechanism to set the taper tightly. When the tool holder is operated with its axis of rotation oriented vertically, the tool holder is dropped a short distance, so as to seat the taper. Gravity is sufficient to insure that the tool holder does not rise up. However, it is a problem with this known arrangement that the cost of a precision spindle, limits to the accuracy of centering the tool holder resulting from mismatch with the conical surface, and interference signals resulting from the additional suspended and spinning weight significantly limit the precision of the balance that is achieved.
It is, therefore, an object of this invention to provide an arrangement for supporting rotatively a workpiece having a conical surface. It is another object of this invention to provide an arrangement that supports a conical workpiece rotatively without chattering or binding.
It is also an object of this invention to provide an arrangement for supporting rotatively a conical workpiece wherein all points of contact with the workpiece have the same surface velocity.
It is a further object of this invention to provide an arrangement for supporting rotatively a workpiece to be balanced, having a conical surface wherein contribution to an unbalance signal by the supporting structure can easily be identified and separated from the unbalance signal component associated with the workpiece.
It is additionally an object of this invention to provide an arrangement for supporting a conical workpiece that facilitates measurement of static and dynamic unbalance of the workpiece.
It is yet a further object of this invention to provide an arrangement for supporting rotatively a workpiece having a conical surface wherein the workpiece can readily be driven to rotate at a balancing speed.
It is also another object of this invention to provide an arrangement for supporting rotatively a workpiece having a conical surface, the arrangement employing a non-rotating support element.
It is yet another object of this invention to provide an arrangement for supporting rotatively a workpiece having a conical surface for centering same, in combination with a second surface of the workpiece, which may be a substantially perpendicular flange face, for squaring the workpiece.